Photographic process.



W. F. FOX.

PHUTDGHAPHIC PROCESS.

APPLlcAUoN mtu MAY29,1914.

1,166,122. Patented Dec. 28, 1915.

A TTDRNEY UNlTED STATES PATENT OFFICE.

WILLIAM FRANCIS FOX, OF NEW YORK, N. Y., ASSIGNOB 0F TWO-THIRDS T0 KINEMA- COLOR COMPANY 0F AMERICA. 0F NEW YORK, N. Y., A CORPORATION OF DELA- WARE.

PHOTOGRAPHIC PROCESS.

Patented Dec. 28, 1915.

Application 1ed May 29l 1914. Serial No. 841,708.

T0 all 'whom it may concern Be it known that l, W'lLLIAM FRANCIS Fox, a subject of the King ot' Great Britain, residing at Beechhurst, in the borough of Queens, city and State of New York, have invented certain new and useful Improvements in Photographic Processes, of which the following is a specification.

It is a well known fact that the silver deposit upon a photographic print can be changed to practically any color by toning. It is also equally well known that gelatin emulsion can be dyed. Ordinarily upon dyeing such a print, all portions of' the gelatin will take up the dye equally, and even should the black portion of the film have been toned to a different color, there will be a mixing of the colors which will degrade both the tints used. neither color showing properly. The print may, however, be treated chemically, as a result of which not only will the black silver-deposit be turned green, but the gelatin will be so affected as that if the print be immersed in a dye bath, such gelatin will take up dye in inverse proportion to the amount of the silver-deposit which has been turned green. For example, a print containing a portion represented by clear gelatin, another portion represented by gray deposit, and another portion by black deposit, after being toned will give the following results The black deposit will be turned dark green, the gray will be turned a lighter green, and the clear portion will not be affected at all as to color. Dueto the acid contained in the toning bath, however, an action has taken place in the gelatin itself, hardening that portion which has been exposed to light (i. e., the black portion) but leaving in its original state the gelatin which has not been so exposed (i. e., the clear portion). If, now, the print be immersed in a red dye, the clear portion will take up the maximum quantity of such dye, the light green portlon will take up a'less quantity of the dye, and the dark green portion will take up sub stantially no dye. As a result, in the toned and tinted print, the clear portion will be red, the dark portion will be green, and the lighter green portion will be white (or nearly so), this being the result of the comblned colors red and green. Such a result, of course, is unnatural, since the reproduo tion of the natural colors would require that the clear portion of the picture be white, instead of red. Now, if two photographic images be taken upon a panchromatic plate or film, one through a red screen or filter and the other through a green screen or filter, in the negative image taken through the red screen the red portions of the object portrayed will be black, the white portions will be black, and the green portions will be clear. In the negative image taken through the green screen or filter, the red portions will be clear, the 'white portions black, and the green portions black. Obviously in a positive reproduction from each image the conditions here stated will be reversed. Of these four picture-bearing devices (two negatives and two positives), two, z'. e., the green negative and the red positive, will present the proper conditions for toning and dyeing so far as concerns those portions of the object photographed which Were red and green, but not as to those portions which were White. If either the green negative or the red positive were toned and dyed, both the reds and greens would be properly reproduced, but in the negative the portion which should be white would be green and in the positive the portion which shouldbe white would be red. If, however, the red negative and the green positive be superimposed and a print taken therefrom, the required results will be ob` tained, since theredsy Will be clear, (there being, in the superimposed images, two thicknesses of silver deposit representing that color, and consequently practically no exposure therethrough), the whites will be gray, (there being, in said images, but one thickness of silver deposit through which exposure is made), and the greens will be black, (there being, in said images, substantially no silver deposit representing that color). Therefore, to obtain a positive print suitable for coloring, it is essential to supertive of one color and a negative of the other color, in order to get the correct color gradation.

In an application heretofore led by me (Serial No. 807,1T2,filed December 17,1913), I disclosed, as a preferred process, a method of producing an image, suitable, for instance, for projecting purposes, by using a printing negative, the image of such printing negativembeing formed by combined impressions from the image of the green negative and that of the red positive, these being superimposed. While this method involves certain practical advantages, it possesses the disadvantage of requiring an extra length of film coextensive with that employed for the final positive. As pointed out in said application, a positive print bearing, superimposed thereon, the images of the red negative and the green positive, can itself be colored, according to my process, and so made what I term the projecting positive, and it is the purpose'of the present application to cover the process, herein indicated, not involving the use of the intermediate or printing negative.

IVhether the images of the green negative and the red positive be superimposed upon a printing negative as under my former application) or upon the projecting positive itself, all green portions upon the (combined) image will be represented by silver deposit, while all red portions will be represented by clear portions upon the film. Consequently, also as pointed out in said former application, an additional and modifying step of the process will be necessary to effect the proper grading ,or merging of these colors and to thereby reproduce the hues of the object originally photographed. This is accomplished by superimposing upon the (combined) image upon the proyecting positive another image of the same subjectmatter. Since white is the most brilliant portion of a picture, it should be the clearest portion of the positive. Other colors, light or dark, must be supplied as in the object originally photographed. Therefore, for fthe production of the (superimposed) black and white impression upon the color picture, the original negatives (one made through a red screen and the other through a green screen) may be used, a print from each being superimposed over the print upon the projecting positive which has been. or is to be, colored, the exposure of each of said negatives being one-half that normally required, so that the successive exposure of both shall give an impression of normal intensity. As a result, in the impression thus made upon the projecting positive (and which I term the correcting image), the whites will be clear (there being no exposure from either negative), the reds and greens and other colors of the original object will be slightly darker (depending, of course", on the intensity of these colors in such object), and the blacks will be black. The projecting positive will thus bear two images (either on one side or 'on both sides of the film, as presently explained), one of these being in color and the other in monochrome, both being in precise register and the combination of the two giving substantially correct color values. It may be observed that since but two colors have been employed, it will be desirable, in the coloring step, to use, instead of a pure green, a somewhat bluish green; as a result, blue-violet color in the object photographed is not missed, the two primary colors, modified as here indicated, doing the work of three, the object being reproduced in substantially the colors which characterized it.

Stating the theory of the process in another way, it should be noted that when the red negative and the green positive are superposed and a print taken therefrom, the two images neutralize each other as to the whites, grays and blacks, since a part which is black in the negative will be White in the positive, and vice versa. A part which is solid green in the original, however, will be black in the composite print, and lighter shades of green will be a less heavy black, while parts which are red in the original will be clear. Colors tending more to green or red will come out more or less black on the print. When the print is now toned green, as stated, the image is turned green with a shade or intensity proportional to the strength or depth of the silver deposit at each point on the print. The red dyeing operation imparts color to the print in a shade or Vstrength which is inversely proportional to the amount of the silver deposit whlch has been turned green, or, inversely proportional to the extentto which the emulsion of the rint has been affected by the first bath. he grays of the print will take some of the green and some of the red, according to which color predominated in the object photographed. By this process the print is given the colors which passed through the two filters used in making the negatives. The monochrome correcting irnagewhich is superposed on the colored composite improves the clearness of the blacks and the whites and the shading of the colors. A method of practising my invention is mdicated in the accompanying drawing, in which- `Figures 1 and 2 are plan views, respectively, of a negative film and a positive film made from a portion of said negative film. the objects photographed in these and the other figures being two crosses, one red and the other green, against a white background,

the red cross being that at the left. Figs.

4 and 5 are plan views, illustrating the production of what I term the .color image on the projecting positive, Fig. 3 showing the print made from the red negative (Fig. 1),

ig. 4 theprint made from the green positive (Fig. 1), and Fig. 5 the result of the superimposition of the images shown in Figs. 3 and 4. Figs. 6, 7 and 8 are plan views, illustrating the production of what I term the correcting image on the projecting positive and in precise registry with the color image thereon, Fig. 6 illustrating the print made from the green negative (Fig. 1), Fig. 7 the print made from the red negative (Fig. 1), and Figu8 showing the result of the superimposition of the images shown in Figs. 6 and 7. Fig. 9 is a plan view of the projecting vpositive shown in Figs. 5 and 8, the image thereon being the color image as modified by the correcting image.

In carrying out the invention for the particular purpose selected for this disclosure, I first photograph the subject by means of a camera employing the red and green filters above referred to. as in the production of negatives by the kinemacolor process. As a result of the movement of the film and corresponding alternation of the red and green filters, a negative A (Fig. 1) is produced, each two adjacent images upon which will differ in the respect that one, photographed through the green filter. will contain no red sensations, while the other, photograph through the red filter, will contain no green sensations. These two images will be termed herein the green image and the red image respectively. A positive print from such a negative would be suitable for the production of colored moving-pictures if proiected through green and red filters, as hereinabove stated. Instead. however, I utilize this negative only indirectly in the production of the projecting positive, so that the latter may be utilized for the projection of colored pictures in an ordinary projecting apparatus employing no filters. In so doing, after developing and toning the negative, I print therefrom a` positive, B (Fig. 2), which may, if desired, be a reproduction of the entire negative film. Inasmuch, however, as in the further steps of the process I use preferably only the green images upon this positive film, it will be seen that this practice would involve a waste of material, the positive film being twice as long and containing twice as many images as are really required in the practice of the process` Accordingly, I prefer, for reasons of economy, to produce from the original negative a half-length film B, bearing thereon only images printed from the original green negatives. (Or, considering the invention apart from the requirements of moving picture reproduction and assuming that the negative contains but two images, one

green and one red, of the object photogra hed, the positive made therefrom will be ut one-half the length of the negative, since it will bear only a reproduction of the green image of Vsuch original negative). I then produce what I term a color image upon the projecting or exhibition positive (Figs. 5, 8 and 9). This may be done by Superimposing the red negative and the green positive and printing therefrom upon an emulsioned strip C of transparent or translucent material. Or, if preferred, the same result can be accomplished not by superimposing the red negative and green positive but by printing the images thereof successively and in precise register upon said projecting positive C. As will be seen, the resulting image upon the projecting positive will be the same in either event. It will also be seen that, again considering the invention from the standpoint of the requirements of moving picture projection, the images upon the projecting positive will be but one-half the number of images upon the original negative, and that the film containing the former will, therefore. be iust one-half the length of the negative film. Finally, it will be seen that the image impressed upon the projecting positive in the manner just described will contain both red and green color values, due to the use of the red negative (Fig. 3) and the green positive (Fig. 4), as herein directed. The color image thus impressed upon the projecting positive may be treated, to receive the color, either before or after the superimposing thereon of the correcting image in black and white, as presently explained. Again, the color image and the monochrome image may be superimposed either upon opposite sides of the projecting positive film or upon the same side. In the former case, I employ film provided on both sides with suitable emulsion. Inthis event, the exposure involved in the impressing of the color image upon said film is so timed as that the emulsion upon the reverse side of the filmwill remain unaffected by light. When, however, both the color image and the correcting image are superimposed upon the same side of the film, it will be found desirable, after impressing the color image upon said film, to proceed with the coloring step of the process and then to waterproof or otherwise isolate and protect that side of the film preliminarily to remulsioning said side of the film to permit itto receive the correcting image, as hereinafter explained, and also to protect it from the action of the bath used in the development of the monochrome image. Essentially, however, the coloring step of the process will be the same in either case, and this step I now proceed to describe.

I first immerse the projecting positive film in a bath which will have the effect of turning green, in varying degree, the silver deposit of the image thereon. A suitable bath may be compounded of the following constituents (lxalic acid 100 grainsl lVzitei, sufficient to make the total composition twenty ounces.

Immersion of the film in this bath for five minutes will ordinarily be sufiicient. After it has been removed from such bath, it may be washed to remove superfluous material, after which to clear the image and make it more transparent, it may be immersed in an ordinary acid fixing bath, such as is commonly employed, andv in this it is allowed to remain for a suiiicient time to accomplish the purpose stated. Upon removal therefrom, the film may be washed sufliciently to remove superuous sodium thisulfate. The film is then immersed in a bath containing a suitable red dye, for instance an anilin dye, and in this bath it is allowed to remain until any white object in the image shows white. The remaining colors will then he of correct intensity. After removal from the bath, the film may be rinsed to remove superfluous red dye, after which it is dried and the process, so far as concerns the completion of the color image is then complete.

Under the assumption that the coloring step of the process has been performed at this point and not deferred until after the production of the correcting image (as it may be where double emulsion stock is employedl, the next step of the process is to superimpose the correcting image upon the color image. If single emulsion stock be used, the emulsioned surface of the projecting positive is first protected by means of a suitable substance (for example, a celluloid solution), after which that surface is reemulsioned to adapt it to receive the correcting image. Then, the green and red images of the negative are, either by direct or optical printing, and either successively or simultaneously, as preferred, impressed upon the remulsioned surface of the projecting positive film and in precise registry with the color image already impressed thereon. This process is illustrated in Figs. 6, 7 and S, Figs. 5 and S illustrating the same film (the projecting positive), the first-named, however, showing the color image thereon and the lastnamed showing the correcting image superimposed upon said color image. The result of such superimposition of color image and correcting image is illustrated in Fig. 9. It only remains to develop and fix this (monochrome) image, which may be done in the usual or any other suitable manner, after which the projecting positive is complete and ready for use.

I desire it to be understood that in my reference, throughout this specification, to the use of motion picture photography, and in my use of such expressions as the projecting positive, etc., it is not intended to limit this invention to use in connection with the moving picture art, for, as will be readily seen, the invention is of broader scope, quite capable of utilization for the production of discrete pictures, in which, as a result of the process herein disclosed, practically the colors which characterize the object originally photographed will be faithfully reproduced.

Having now described my invention,what I claim as new therein and desire to secure by Letters Patent is as follows:

l. A photographic process comprising the production of two` negatives of an object, from one of which red color sensations have been omitted and from the other of which green color sensations have been omitted, obtaining a positive print on transparent cr translucent material from said first named negative, producing by means of the positive print and said second negative a reproduction of the (superimposed) images thereon on emulsioned transparent or translucent material, treating said reproduction in a bath adapted to cause the silver deposit thereon to assume a green color, of an intensity proportional vto the strength of the deposit, and to affect the emulsion thereof, in direct proportion to the extent to which it has been exposed to light, and treating the reproduction with a bath adapted to impart a red color thereto, in inverse proportion to the extent to which the emulsion thereof has been aii'ected by said first bath, substantially as set forth.

2. A photographic process comprising the production of two negatives of `an object, from one of which certain color sensations have been omitted, and from the other of which certain other complementary sensations have been omitted, obtaining a positive print on transparent or translucent ma- 115 terial fromY one of said negatives, producing a print on emulsioned transparent or translucent material, of the superposed ima es of said positive print and the other o said negatives, treating the print thus made with 120 a bath, adapted to cause the silver deposit on the print to assume a color corresponding to color sensations included in the image on the last-named print, of an intensity proportioned to the strength of the deposit, and to 125 affect the emulsion of the print, in proportion to the extent to which it has been exposed to light, and treating the print with a bath adapted to impart a` complementary color thereto, in inverse proportion to the 130 extent to which the emulsion thereof has been affected by said first bath, substantially as set forth.

3.- A photographic process comprising-the production of two negatives, of an object, from one of which certain color sensations have been omitted, and from the other of which certain other complementary sensations have been omitted, obtaining a positive print on transparent or translucent material from one of said negatives, producing a print on elnulsioned transparent or translucent material, of the superposed images of said positive print and the other of said negatives, treating the print thus made with a bath, adapted to cause the silver deposit on the print to assume a color corresponding to color sensations included in the image on the last-named print. of an intensity proportioned to the strength of the deposit, and

`to afi'ect the emulsion of the print, in proportion to the extent to which it has been exposed to light, and treating the print with a bath adapted to impart a complementary color thereto, in inverse proportion to the extent to which the emulsion thereof has been affected by said first bath, and reproducing on said material, in registrywith said superposed images, a monochrome image made from said two negatives, substantially as Aset forth.

A photographic process involving the production of a negatife of tWo images from one of which` certain color sensations have been omitted and from the other of which certain other color sensations have been omitted, obtaining a positive print on transparent'or translucent material from one of said negative images, producing by means of the positive print and the other of said negative images a reproduction of the (superimposed) images thereon on transparent or translucent material, treating said reproduction with complementary colors corresponding substantially with the color sensations omitted from said negative and reproducingr the images of said negative upon said last-named material in registry with the image already impressed thereon, substantially as set forth.

5. A photographic process involving making two negatives, one through a filter of one color and the other through a filter of another color, printing a positive of one of said im ges, obtaining a composite print from said positive and one of said negatives, coloring the same to impart a color to the image, corresponding to the color of one filter, in shades varying with the strength of the silver deposit, and to impart a color, to the rint, corresponding to that of the other iiter, in shades varying approximately in inverse proportion 'to the extent to which the emulsion of the print has been exposed to light, and superimposing in registry therewith a rint from both of said negatives, substantially as set forth.

This specification signed and witnessed this 27th day of May, 1914.

WILLIAM FRANCIS FOX. Witnesses:

S. O. EDMoNDs, I. MCINTosII,

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of latents,

Washington, D. C.

It is hereby certified that in Letters Patent No. 1,166,122, granted December 28,

1915, upon the application of William Francis Fox, of NewI York, N Y., for an improvement in Photographic Processes, errors appear in the printed specifica.- tion requiring correction as follows: Page 3, lines 33-34, for the Word "photograph read photographed; page 4, line 25, for the Word thisu1fate" read th'iosulfate; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oice.

Signed and sealed this 15th day of February, A. D., 1916.

[SEAL] R. F. WHITEHEAD,

Acting Commissioner of Patents. 

